feat: cloudwatch logs transformer support (#34863)

### Issue # (if applicable)

Closes #34861.

### Reason for this change

Creates CDK constructs for CloudWatch Logs Transformers. Transformers already have CFN constructs and this achieves functional parity.

### Description of changes

Added a `Transformer` construct which is an abstraction over `cfnTransformer`.

Created a factory class `ProcessorFactory` with static methods to create each of the 5 overarching types of processors described in https://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/CloudWatch-Logs-Transformation-Processors.html, namely: `ParserProcessor`, `VendedLogParser`, `StringMutatorProcessor`, `JsonMutatorProcessor` and `DataConverterProcessor`. 
These classes implement a `_bind()` method responsible for returning the props expected by CFN constructs for each processor of the respective types.
These classes are further split into their processors defined by enums (`ParserProcessorType`, `VendedLogType`, `StringMutatorType`, `JsonMutatorType`, `DataConverterType`) and properties for each processor.

A `Transformer` expects a `transformerConfig` which is a list of processors. Processors can be created using the static methods `createParserProcessor`, `createVendedLogParser`, `createStringMutatorProcessor`, `createJsonMutatorProcessor` and `createDataConverterProcessor` in the `ProcessorFactory`, by passing the type (from the enums defined above) and the relevant props for that processor. `ValidationError` is thrown if the expected/required props are not passed.

Further validations are performed for limit breaches or positions of parsers being incorrect.

### Describe any new or updated permissions being added

-


### Description of how you validated changes

Added unit tests for each processor and each validation. Added integ test.

### Checklist
- [X] My code adheres to the [CONTRIBUTING GUIDE](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md) and [DESIGN GUIDELINES](https://github.com/aws/aws-cdk/blob/main/docs/DESIGN_GUIDELINES.md)

----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: Abhijoy-Mandal

packages/@aws-cdk-testing/framework-integ/test/aws-logs/test/integ.loggroup-transformer.js.snapshot/aws-cdk-transformer-integ.assets.json

@@ -0,0 +1,82 @@
+{
+ "Resources": {
+  "MyLogGroup5C0DAD85": {
+   "Type": "AWS::Logs::LogGroup",
+   "Properties": {
+    "RetentionInDays": 731
+   },
+   "UpdateReplacePolicy": "Retain",
+   "DeletionPolicy": "Retain"
+  },
+  "MyLogGroupResourceTransformer00531468": {
+   "Type": "AWS::Logs::Transformer",
+   "Properties": {
+    "LogGroupIdentifier": {
+     "Ref": "MyLogGroup5C0DAD85"
+    },
+    "TransformerConfig": [
+     {
+      "ParseJSON": {
+       "Source": "customField"
+      }
+     },
+     {
+      "AddKeys": {
+       "Entries": [
+        {
+         "Key": "test_key1",
+         "OverwriteIfExists": true,
+         "Value": "test_value1"
+        },
+        {
+         "Key": "test_key2",
+         "OverwriteIfExists": false,
+         "Value": "test_value2"
+        },
+        {
+         "Key": "test_key3",
+         "OverwriteIfExists": false,
+         "Value": "test_value3"
+        }
+       ]
+      }
+     }
+    ]
+   }
+  }
+ },
+ "Parameters": {
+  "BootstrapVersion": {
+   "Type": "AWS::SSM::Parameter::Value<String>",
+   "Default": "/cdk-bootstrap/hnb659fds/version",
+   "Description": "Version of the CDK Bootstrap resources in this environment, automatically retrieved from SSM Parameter Store. [cdk:skip]"
+  }
+ },
+ "Rules": {
+  "CheckBootstrapVersion": {
+   "Assertions": [
+    {
+     "Assert": {
+      "Fn::Not": [
+       {
+        "Fn::Contains": [
+         [
+          "1",
+          "2",
+          "3",
+          "4",
+          "5"
+         ],
+         {
+          "Ref": "BootstrapVersion"
+         }
+        ]
+       }
+      ]
+     },
+     "AssertDescription": "CDK bootstrap stack version 6 required. Please run 'cdk bootstrap' with a recent version of the CDK CLI."
+    }
+   ]
+  }
+ }
+}

packages/@aws-cdk-testing/framework-integ/test/aws-logs/test/integ.loggroup-transformer.js.snapshot/aws-cdk-transformer-integ.template.json

@@ -0,0 +1,37 @@
+import { IntegTest } from '@aws-cdk/integ-tests-alpha';
+import { App, Stack, StackProps } from 'aws-cdk-lib';
+import { JsonMutatorType, LogGroup, ParserProcessorType, ParserProcessor, JsonMutatorProcessor } from 'aws-cdk-lib/aws-logs';
+
+class TransformerIntegStack extends Stack {
+  constructor(scope: App, id: string, props?: StackProps) {
+    super(scope, id, props);
+
+    const logGroup = new LogGroup(this, 'MyLogGroup');
+    const jsonParser = new ParserProcessor({
+      type: ParserProcessorType.JSON,
+      jsonOptions: { source: 'customField' },
+    });
+
+    const addKeysProcesor = new JsonMutatorProcessor({
+      type: JsonMutatorType.ADD_KEYS,
+      addKeysOptions: {
+        entries: [
+          { key: 'test_key1', value: 'test_value1', overwriteIfExists: true },
+          { key: 'test_key2', value: 'test_value2' },
+          { key: 'test_key3', value: 'test_value3', overwriteIfExists: false },
+        ],
+      },
+    });
+
+    logGroup.addTransformer('Transformer', {
+      transformerName: 'MyTransformer',
+      transformerConfig: [jsonParser, addKeysProcesor],
+    });
+  }
+}
+
+const app = new App();
+const testCase = new TransformerIntegStack(app, 'aws-cdk-transformer-integ');
+new IntegTest(app, 'transformer-create', {
+  testCases: [testCase],
+});